Left picture: This child´s enema shows a congenital megacolon; a typical transitional zone is unfortunately not well defined at the site of transition of the left hemicolon and of the distally elongated loop of the megasigma to the rectum.
Right picture: Here, the diagnosis is an idiopathic megarectum due to a long-standing constipation because signs of a Hirschsprung´s disease are missing. The rounded mass is a large coprolith.
Left picture: In the picture at the bottom with the operative findings of the same case, the megasigma = elongated distal sigmoid loop of the contrast enema of the picture is recognizable, and the radiologically not documented transition zone on the right side of the downward running rectum as well.

In both patients a contrast enema has been performed because constipation was the leading symptom. In both patients an elongated sigmoid flexure on the right side is visible, reaching nearly to the upper abdomen.
Right picture: The contrast has been evacuated nearly completely and a round rectum becomes visible being severely dilated and containing a mass. The colon is inconspicuous.
Left picture: The left hemicolon, the sigmoid colon, and the rectum are filled with contrast; the sigmoid loop which lies on the right side is very wide, shows no haustration, and has an irregular contour of the wall.